This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The overall goal of the present study is to develop a system for long[unreadable]lasting inhibition of gene expression in the brain or ovary that can be used to cause permanent infertility in dogs and cats. This application is a collaborative effort between the University of Iowa (UI) and the Oregon National Primate Research Center (ONPRC). We have performed several experiments aimed at achieving the objectives of the original application. These experiments involve the use of a bio-panning strategy to identify peptide epitopes that can be delivered via the blood stream and specifically home to cells in either the hypothalamus or the ovary of the rat to deliver RNAi. After five rounds of bio-panning, we selected an epitope that specifically home to the hypothalamus, ovary or both, and that can therefore be used for the next phase of the study: re-directing viral tropism of AAV based on these selected epitopes to deliver RNA interference to those particular cell populations.